/* POSIX barrier implementation for LinuxThreads. Copyright (C) 2000 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Kaz Kylheku <kaz@ashi.footprints.net>, 2000. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include <errno.h> #include "pthread.h" #include "internals.h" #include "spinlock.h" #include "queue.h" #include "restart.h" int pthread_barrier_wait(pthread_barrier_t *barrier) { pthread_descr self = thread_self(); pthread_descr temp_wake_queue, th; int result = 0; __pthread_lock(&barrier->__ba_lock, self); /* If the required number of threads have achieved rendezvous... */ if (barrier->__ba_present >= barrier->__ba_required - 1) { /* ... then this last caller shall be the serial thread */ result = PTHREAD_BARRIER_SERIAL_THREAD; /* Copy and clear wait queue and reset barrier. */ temp_wake_queue = barrier->__ba_waiting; barrier->__ba_waiting = NULL; barrier->__ba_present = 0; } else { result = 0; barrier->__ba_present++; enqueue(&barrier->__ba_waiting, self); } __pthread_unlock(&barrier->__ba_lock); if (result == 0) { /* Non-serial threads have to suspend */ suspend(self); /* We don't bother dealing with cancellation because the POSIX spec for barriers doesn't mention that pthread_barrier_wait is a cancellation point. */ } else { /* Serial thread wakes up all others. */ while ((th = dequeue(&temp_wake_queue)) != NULL) restart(th); } return result; } int pthread_barrier_init(pthread_barrier_t *barrier, const pthread_barrierattr_t *attr, unsigned int count) { if (count == 0) return EINVAL; __pthread_init_lock(&barrier->__ba_lock); barrier->__ba_required = count; barrier->__ba_present = 0; barrier->__ba_waiting = NULL; return 0; } int pthread_barrier_destroy(pthread_barrier_t *barrier) { if (barrier->__ba_waiting != NULL) return EBUSY; return 0; } int pthread_barrierattr_init(pthread_barrierattr_t *attr) { attr->__pshared = PTHREAD_PROCESS_PRIVATE; return 0; } int pthread_barrierattr_destroy(pthread_barrierattr_t *attr) { return 0; } int __pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr, int *pshared) { *pshared = attr->__pshared; return 0; } int pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared) { if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED) return EINVAL; attr->__pshared = pshared; return 0; }